Bacteria producing extended-spectrum
beta lactamase (ESBL) are detected mainly in adult urinary specimens, and are believed to cause hospital-acquired
infection due to their resistance to many drugs. The incidence of
community-acquired infection due to such bacteria is increasing, but few cases of infant upper
urinary tract infection (UUTI) have been reported in Japan. We treated four infants with UUTI caused by ESBL-producing Escherichia coli, as determined by genotyping. Using medical records, we retrospectively evaluated the
clinical course,
antibiotic use and efficacy, antimicrobial susceptibility results, and the presence of underlying disease. One of the four had been previously hospitalized for occult
bacteremia. Two developed UUTI after
antibiotic treatment, indicating that previous
antibiotic use may have been a risk factor in these cases. We could not identify the
infection route in all cases. Two of the four had bilateral
vesicoureteral reflux (VUR). Renal scintigraphy was done in three. Although an initial
dimercaptosuccinic acid (
DMSA) defect was detected in all four, only one had renal
scarring. E. coli isolates from all four showed PCR signals for blaCTX-M-; one isolate positive for the blaCTX-M3 group and three positive for blaCTX-M14. Antimicrobial susceptibility test results showed all isolates to be resistant to
cephalosporins, but discrepancies existed between antimicrobial susceptibility results and actual clinical efficacy. Clinically,
cefazolin (CEZ) was effective in two subjects and
ceftazidime (CAZ) effective in one.
Panipenem/betamipron (
PAPM/BP) was effective in one. None of the four developed
sepsis or
meningitis. Post hospitalization
antibiotic prophylaxis showed that none of the four has had UUTI recur. Japan's ESBL-producing
bacterial infection incidence is increasing, so medical professionals should watch for such UUTI even in first-case occurrence in infants.